Manufacture of motor fuel



April 20, 1943. v A. R. GQLDS BY 2,317,142 MANUFACTURE OF MOTOR FUEL Filed April 27; 1939 FRACTIONATORS SEPARATOR REACTION CHAMBERS ARTHUR R. GoLosa Y INVENTOR ATTORNEYS Patented Apr. 210, 1943 MANUFACTURE OF MOTOR FUEL Arthur Goldsby, Beacon, N. Y., asslgnor, by

mesne assignments, to New York, N. Y., a corporation of Delaware Application April 27, 1939, Serial No, 270,338

8 Claims.

This invention relates to the conversion of hydrocarbon oils and gases-and has to do particularly with the production of high antiknock hydrocarbons suitable for the manufacture of motor fuel, such as aviation gasoline.

In accordance with the invention, hydrocarbon charging stock of higher molecular weight than butane is subjected to conversion at temperatures lower than normal cracking temperatures in the presence of a catalyst, whereby a substantial amount of normally gaseous hydrocarbons is formed, containing a large proportionof isobutane. The isobutane, or fraction containing the isobutane, in the presence of normally gaseous oleflns, is treated with an alkylation catalyst, whereby the isobutane is alkylated by the oleflns to form high antiknock hydrocarbons; such as branched chain, normally liquid hydrocarbon within the gasoline boiling point range. It has been found that hydrocarbon oils, preferably parafllnic hydrocarbons of the lower boiling point series, may be cracked and isomerized and preferably between under proper conditions and in thepresence of a suitable catalyst, to produce a large yield of branched chain or isoparaihn hydrocarbons. The normally liquid hydrocarbons may simultaneously be substantially increased in antiknock property and the reaction is peculiar in the production of a substantial quantity of normally gaseous hydrocarbons predominating in isobutane. In this way, it is possible to produce from normally liquid hydrocarbons, normally gaseous hydrocarbons, containing or more of isobutane and substantially free from olefins.

In the alkylation of the isoparaflins produced by the catalytic conversion operation, isobutane, for example, is treated in the presence 01' olefinic hydrocarbons, preferably normally gaseous olefins with an alkylation catalyst to effect alkylation of the isobutane with the oleiins to form hi her molecular weight, normally liquid hydrocarbons of high antiknock value, including iso-octanes. In the alkylation operation it is desirable to use a charging stock containing a high proportion of isobutane which may not be always readily available from natural sources. The present invention insures an adequate supply of isobutane and provides a unitary process for the production and alkylation' of isobutane to produce high antiknock gasoline hydrocarbons.

The charging stock to the catalytic conversion operation may be any hydrocarbon oil which yields on treatment with a catalyst of substantially the cataytic properties of aluminum chloride and hydrogen chloride, a substantial yield of halide may be about 5 to 10% The Texas Company,

high antiknock gasoline and isobutane. It has been found that a paramnic oil is suitable and preferably a low boiling naphtha fractio such as one boiling within the range'of about 97-220 F. A paraflinic or straight-run naphtha from a paraflin base crude gives good results.

The conversion operation is carried out at temperatures below those normally used in cracking and diflers from a cracking operation in that no large amount of unsaturated normally gaseous products is obtained. The reaction apparently consists largely of isomerization with some splitting of the higher boiling oils into lower boiling liquid and normally gaseous isoparaiiins. The temperatures usedmay be about to 400 F. about and 300 F., al-, though considerable latitude is intended. Good. results have been obtained at about 200" to 250 F. Pressure of '75 to 150 pounds per square inch may be used although atmospheric temperatures are often satisfactory. The process may be carried out under milder conditions than normal cracking operations and, as contrasted to cracking, wherein heavier higher boiling molecules are converted into lower boiling products" including aromatics, olefins and paraflins, the present operation produces low boiling products of substantially saturated and largely of branched chain type. The catalyst used may be an anhydrous metallic halide, such as an anhydrous aluminum chloride or bromide, and preferably a mixture of a metallic halide and a hydrogen halide promoter, such as hydrogen chloride or hydrogen bromide. The time of reaction depends on the temperature. At low temperature, the time is relatively long and may range hours, for example between about 2 to 20 hours. At higher temperatures the time may be much shorter, such as 1 minute to 1 hour. The amount of catalyst in batch operation may range from 2 to 50% and preferably about 5 to 10% by weight, based on the hydrocarbon charged. In continuous operations the amount of catalyst will vary and may be considerably less.

of the metallic halide and usually is around 2% or less.

In the alkylation step it is preferable to use normally gaseous hydrocarbons between 2 and 5 carbon atoms, such as C3 or Cl hydrocarbons or a mixture thereof. A portion of these is derived from the paraflin hydrocarbons formed in the above described conversion operation, for example, isobutane or a hydrocarbon fraction containing a large amount 'or-predominating in isobutane, such as a mixture of isobutane and norfrom about 2 to 50 The hydrogen mal butanes or a mixture of isobutane, normal butanes and propane. The above paraflin charging stock is mixed with olefinic hydrocarbons which may be oleflns of substantially thesame number of carbon atoms derived from the cracking of hydrocarbon oils or gases. such as cracking still gases or refinery gases, or oleflns resulting from the cracking or dehydrogenation of normally gaseous paraflin hydrocarbons. A C4 hydrocarbon fraction, or a mixture of C4 and Ca hydrocarbons, comprising cracked products, is preferable, and it is desirable that the ratio of isoparaflins to olefins in the mixed feed be fairly high, for example at least about 1:1 and preferably between about 3:1 and 5:1. The excess isoparaflins, such as isobutane are recycled. The mixture of isoparafilns and olefins'is intimately contacted at temperatures of about 0 F. to 100 F. and preferably about 60 to 90 F'., with strong sulfuric acid, for example sulfuric acid of about i 90 to 100% strength, and'preferably about 94 to,

98%. The reaction is carried out under sufficient pressure to maintain a liquid phase, .for example, from about atmospheric to fift unds. The products comprise largely normally liquid branched chain, or isoparaifin hydrocarbons of v fractionator 25. In the fractionator 25 it is 111-- a from the unsaturated oil which may be used for the manufacture of resins.

The oil substantially free from the catalyst is drawn from'the upper portion of the separator 2| througfi the line 24 and introduced into'a 4 to separate the metal compounds tended to make a separation between the norlifi The normally liquid hydrocarbons may be withhigh antilmock value suitable for the manufacture of gasoline.

In practicing the invention it is advantageous to blend the gasoline from the alkylation operation with the gasoline from the naphtha conversion step. The stabilized alkylation gasoline has a relatively high antiknock value'but also high and 50% boiling points, whereas the isomerized naphtha may be of somewhat lower octane number but a low 50% boiling point and especially low on points below 50%. The resulting blend will have a fairly high octane number and about the desired 50% boiling point. It is possible in t is way to obtain a product which will meet 'he required specifications of an aviation gasoline.

The invention will be more fully understood by the following description read in connection with the accompanying drawing which shows diagrammatically, in elevation, one form of apparatus for carrying out the process of the invention. Referring to the drawing, a hydrocarbon oil. is charged through the line i by the pump 2 tea heating coil 3, located in a furnace 5. In the coil 3 the oil is raised to the desired temperature, and then transferred through the line I to reaction chambers .8 and 9, connected in series by the line' l0, While two reactors are shown, any number may be used, or other means such as a coil may be used. A catalyst, in any suitable form, preferably in a liquid form, such as a suspension in an inert liquid, is introduced through the line [2 by the pump l4. and passed through the valve controlled line [5, which is in communication with the line I, leading to the heating coil 3. The heating coil 3 may be by-passed, if desired, and the catalyst passed directly to the line I through the valve controlled line iii. In the reaction chambers 8 and 9 the oil and catalyst are intimately contacted by means of stirring mechanisms I8 for suiiiclent time to accomplish the desired reaction. The reaction products are transferred from the lower portion of the reaction chamber 9 through the line to a separator 2| wherein the catalyst and sludge separate from the oil and are then withdrawn from the bottom of the separator through the valve controlled line 22. This sludge material may be subsequently treated, for example by hydrolysis,

drawn from the bottom oi the fractionator through the line 26 and discharged from the system through the valve controlled line 28 or recycled to thesystem by pump 30 through the line 3! which communicates with the line I, leading to the heating coil 3. The product drawn oil through line 28 may require further fractionation to obtain a product suitable for use as gasoline. Such fractionation may be obtained by separate distillation or rerunning, or by suitable fractionation in the tower 25. For this purpose, a side stream of the required boiling range may be taken from 'the fractionator through the line 32 and discharged from ,the system or recycled all or in part through the branch line 33 and line 3| to the system; Instead of taking a side stream from the tower 25, it is contemplated that another fractionator may be used for fractionating out a gasoline cut of any desired boiling range. The normally gaseous hydrocarbons are withdrawn from the top of the fractionator25 through the line 25 and introduced into a secondary fractionator 33 in which the gases are fractionated to separate and release through line 31 those of a more permanent nature, such as methane and hydrogen, and all or a portion of the C: and C: hydrocarbons, if desired.

\ The higher boiling normally gaseous hydrocarbons, comprising C4 hydrocarbons, are withdrawn from the bottom of the fractionator 38 by'the pump38 and forced through the line 40 to the allrylation vessels 4| and 42 connected in series by line 44. The alkylation catalyst, such as sulfuric acid, is introduced by the pump 45 through the line 46 whichcommunicates with the line 40.

The olefin charging stock is introduced by the or both. The alkylation vessels 4| and 42 are 7 provided with contacting means, such as stirrers, whereby intimate contact is provided between the mixture of hydrocarbons and the catalyst. The reaction products, pass from the last alkylatlon vessel through the line 53 to a separator 54 wherein the acid separates and may be withdrawn from the' lower portion thereof through the line 55 and discharged from the system or recycled through the line 56 by the pump 51. The hydrocarbons, substantially free from acid, are removed from the upper portion of the separator 54 through the line 59 and discharged into a fractionator 60 wherein a separation is made between the gasoline hydrocarbons and the higher boiling products, or bottoms, which are withdrawn from the bottom of the fractionator through the valve controlled line 3|. The gasoline hydrocarbons are taken overhead through the vapor line 62, condenser 63 and run-down line 64 to a receiver 63. The gasoline in receiverabout 3: 1.

as vapors and may be removed overhead. A stabilized gasoline having higher 10% and 50% boiling points than required to meet commercial aviation gasoline specifications as hereinbefore set forth is withdrawn from the lower portion of tower 68 as bottoms through line 10, and is preferably combined with the isomerized naphtha in line ,32. v

The overhead products comprising isobutane are passed through the vapor line H, condenser I2, and rundown line 13 to a receiver 15. When charging C4 hydrocarbons to the alkylation unit, the product collected in receiver 15 may be chiefly isobutane with or without some n-butane.

In case hydrocarbons lighter than C4 hydrocarbons, such as Ca hydrocarbons, are removed from the top of stabilizer, these hydrocarbons may be separated from the isobutane and used as reflux or discharged from the system. It is contemplated, for example, that the C3 hydrocarbons, in the latter case, may be collected in the receiver 15 and the isobutane removed as a side stream from the stabilizer 68. The latter method of operation is not shown in the drawing. The isobutane is preferably recycled to the alkylation vessels through the line 16 in which is located The tests on the naphtha before and after treatment were as follows:

Distillation (A. S. T. M.) Charge Product Initial boiling point 97 R5 5 4 em 10 119 106 127 117 135 128 141 136 148 144 155 154 163 165 171 182 184 230 199 212 404 97. 5 94. 5 Percent res 1. Percent loss. i 4. Octane number 07. 6 80. 0

The following examples are listed which show the results obtained in the catalytic isomerizapump 18. Any portion of the isobutane may be discharged from the system through branc line 80. 1

Example I I A straight run naphtha from paraffin base crude, having a boiling point range of about 185 to 220 F. and an octane number of about 50, was

mixed with about of anhydrous aluminum bromide and reacted at a temperature of about 200 F. for about 16 hours. About 10% by volume of sludge was formed which was separated from the reaction products. liquid products was obtained,boiling substantially within the boiling point range of the original oil. About volumes of normally gaseous hydrocarbons were liberated, showing the following percentage composition by volume:

Per cent Methane 5.7 Propane 39.1 Normal butane 4.5 Isobutane 50.5

The gaseous hydrocarbons were fractionated to obtain a. C4 fraction comprising about 90% isobutane. This fraction was mixed with a cracked C4. hydrocarbon fraction in such proportion that the ratio of isobutane to olefins was tacted with 94% sulfuric acid in the proportion of about 0.8% by weight based on the olefins and the mixture allowed to react for about one hour at about F. The acid was separated from the reaction products and the hydrocarbons fractionated to obtain a gasoline fraction. The yield of gasoline was about 170% based on the olefins consumed and showed an antiknock value of about 90.

Example II A straight run naphtha was intimately contacted with 18.9% aluminum bromide and 0.9% hydrogen bromide for 6 hours at 199 to 207v F. There was obtained 87.6% of gasoline, 5.4% of gasof which about was isobutane, and 7% hydrocarbons in combination with the catalyst.

About by volume of The mixture was intimately contion of a broad boiling range straightrun naphtha or higher boiling. fraction of straightrun naphtha. By comparison with Example II above, it will be noted that greatly superior results from the standpoints of octane and volatility or boiling point distribution of the isomerizate were obtained in the case of the low-boiling fraction of said Example II; and that the isomerizate of said,Example Ilconstitutes a satisfactory blending stock for alkylation gasoline stabilized to lower 10% and 50% boiling points than required to meet commercial aviation gasoline specifications, to improve the front end volatility of the latter and maintain high octane of the blended product as required to meet said commercial aviation gasoline specifications.

Example 1 H An acid treated straight run naphtha was intimately contacted for 2.5 hours at 230 to v 241 F. and under a pressure of to 131 pounds with 10% aluminum chloride and 0.8% hydrogen chloride. About 91% gasoline, 3% gas and 6% of hydrocarbons in the form of a complex with.

the catalyst were obtained. The gas contained about 83% of isobutane. The tests in the charge and product were as follows:

Example 1v Another example of the naphtha used in Example III was treated with 20% aluminum chloride and 0.8% hydrogen chloride, for 3.3 hours at 238 to 245 F. under a pressure of to pounds. About 76% of gasoline, 13.5% gas containing about 80% isobutane, and 10.5% of hydrocarbons inthe form of a complex with the catalyst, were obtained. The gasoline product showed the following tests:

Percent rec. Percent res Percent loss. 2 Octane number...- 66. Plus 1 cc. tctracthyl lcad Plus 2 cc. tctraethyl lead Example V A straight run acid treated naphtha was treated with 10% aluminum chloride and 0.8% hydrogen chloride for 4.2 hours at 260 to 264 F.

' under a pressure of 80. to 100 pounds. Approximately 89% gasoline, 2% gas consisting of about 77% isobutane and 9% hydrocarbons in the form of a complex with the catalyst was obtained. Thecharge and product tested as follows:

Charge Product Initial boiling point 284 102 5 150 10. 300 192 20 304 266 3o 308 283 40. 311 301 50 315 310 60. 318 316 70. 322 324 S0 i i l 329 334 so 340 364 95 A 352 500 E. l 394 500 Percent rec. 95. 5 Percent res 0. 9' Percent loss 3. 6 Octane number 26. 5 5. 5 Plus 1 cc tetraethyl lead 43 -52 Plus 2 cc. tctraethyl lcarl 52. 5 Go The isobutane in the gases evolved in the above examples is alcylated with C4 or C3 and C4 olefins to produce a gasoline having an octane number of about 90. This product is blended with the isomerized naphtha such as produced in Example II to obtain a blend having an octane number substantially higher than the isomerized naphtha,

the exact amount depending on the amount of alkylate added.

While sulfuric acid has been specified as the catalyst used in the alkylation step, it is contemplated that other alkylation catalysts may be used, such as anhydrous metallic halides, including aluminum chloride or bromide, and hydrofluoric acid. c

This application is a continuation in part of a relatively low anti-knock paraflinic hydrom carbon charging stock of higher molecular weight than butane but boiling below about 212 F. to the action of an anhydrous metallic halide and a hydrogen halide at temperatures above 75 F. but below 400 F. to effect isomerization of the hydrocarbons without the formation of --any substantial amount of unsaturated hydrocarbons, whereby substantially saturated normally liquid hydrocarbons within the gasoline boiling range 0t increased branched chain structure are produced together with normally gase ous, substantially saturated parafllnic hydrocarbons consisting mainly of isobutane, the said charging stock of relatively low boiling range producing under the said isomerizlng' conditions a resultant liquid product of greatly improved antiknock value but having lower 10% and 50% boiling points than desired for commercial aviation gasoline, separating the resulting isomerized normally liquid hydrocarbons from the normally gaseous fraction, allwlating isobutane oi the normally gaseous fraction with low-boiling olefins in the presence of an alkylating catalyst under alkylating conditions to produce substantially saturated hydrocarbons within the gasoline boiling range of high anti-knock value mixed with light normally gaseous hydrocarbons, stabilizing the mixture to remove the light material as vapors and produce a stabilizedalkylatlon gasoline having higher 10% and 50% boiling points than desired for commercial aviation gasoline, and blending resulting isomerized liquid hydrocarbons with resulting alkylate for the production of a commercial aviation gasoline of high antiknocl: value and desired boiling range.

2. A process in accordance with claim 1, in which the alkylating catalyst is concentrated sulfuric acid of alkylation strength.

3. A process in accordance with claim 1, in which the temperature of the isomerization is maintained at about 200 to 250 F.

4. A process in accordance with claim 1, in which the anhydrous metallic halide is-anhydrous aluminum chloride and the hydrogen halide is HCl.

5. A process in accordance with claim 1, in which the parafiinic hydrocarbon charging stock is a low-boiling fraction of straightrun naphtha.

6. In the manufacture of aviation gasoline of alkylated with a low-boiling olefin in the presence of an alkylation catalyst under alkylating conditions to produce hydrocarbon reaction products, the impro ement which comprises fractionating and stabilizing the hydrocarbon reaction.

products to separate hydrocarbons boiling above the aviation gasoline boiling range and also to separate normally gaseous hydrocarbons to thereby produce a resulting stabilized alkylation gasoline having 10% and 50% boiling points above those required to meet commercial aviation gasoline specifications, and then blending with the said stabilized alkylation gasoline a low-boiling fraction consisting essentially of normally liquid saturated hydrocarbons of largely isoparaffinic character and of high anti-knock value, which is the product of catalytic isomerization of a paraflinic hydrocarbon charging stock of higher molecular weight than butane but boiling below about 220 F., said low-boiling fraction having substantially lower 10% and 50% boiling points than required to meet said commercial aviation gasoline specifications, whereby an aviation gasoline of high anti-knock value is obtained which meets said commercial aviation gasoline volatility specifications.

7. Process as defined in claim 6, wherein the said low-boiling fraction is the product 01 catalytic isomerizaticn with an aluminum halide and a hydrogen halide at temperatures of about 75-400 F. of a straightrun parafiinic naphtha fraction boiling within the range of 97 -220 F.

8. In the manufacture of aviation gasoline of high anti-knock rating, wherein isobutane is alkylated with C4 olefins of a C4 hydrocarbon fraction in the presence of an alkylation catalyst under alkylating conditions, and resulting hydrocarbon phase is separated from catalyst phase, the improvement which comprises fractionating and stabilizing the hydrocarbon phase to separate hydrocarbons boiling above the aviation gasoline boiling range and also to separate normally gaseous hydrocarbons to thereby produce a resulting stabilized alkylation gasoline having 10% and 50% boiling points above those required to meet commercial aviation gasoline specifications, and then blending with the said stabilized alkyiation gasoline a low-boiling isomerizate consisting essentially of normally liquid saturated hydrocarbons of largely isoparafiinic character and oi. high anti-knock value resulting from catalytic isomerization of a parafiinic charging stock of higher molecular weight than butane but boiling below about 220 F., said iso merizate having a 10% boiling point at least as low as 106 F. and a 50% boiling point at least as low as 144 F., to thereby produce a resulting gasoline of high anti-knock value meeting said commercial aviation gasoline volatility specifications.

ARTHUR R. GOLDSBY. 

